Many metal wire mesh products comprise a plurality of round longitudinal wires and a plurality of round transverse wires forming a plurality of rectangles. These products include welded wire meshes or wire laths, or other meshes that are twisted or fastened together in some manner at the intersections of the longitudinal and transverse wires. Examples of the first type are welded concrete reinforcing mesh, welded utility mesh, or welded stucco reinforcing lath. An example of the latter type is wire fencing.
For wire meshes of lighter wire sizes, it is common to wind these products into rolls. Rolls provide the advantage of a convenient package containing a considerable length of continuous material. Rolls can provide a compact and dense package, which is important for warehousing and shipping considerations. Further, wire mesh products formed into rolls can easily be placed on pallets for handling.
However, one of the drawbacks of rolling metal wire mesh products into rolls is that the longitudinal wires can take on a curvature set. For the user, such curvature set often presents a problem. When unrolling the product, the longitudinal wires retain a memory and a tendency to spring back to the rolled position. As most products are intended to lay or run flat, or in a straight line, the user must work against the tendency of the mesh to spring back to its rolled condition. This can be dangerous for the user, and makes it difficult to flatten the product as it is being applied or while the wire mesh is being further processed.
The curvature set is caused when the longitudinal wires are bent into the roll shape. The resulting curvature stretches the outside fibres of the metal wires beyond their elastic limit. The metal at the outer side of each wire becomes plastically deformed and retains the memory of this deformation. The curvature set is primarily a function of the wire size, the ductility of the metal and the radius of the roll.
To partially counter the problem of curvature set, some manufacturers have produced rolls having larger core diameters. This approach can reduce the problem to some extent but will not eliminate it entirely, unless inordinately large roll core diameters are used. This approach also results in larger outer roll diameters for the same length of product and therefore, the advantages of a dense package are not fully achieved.
Producing and packaging metal wire mesh in sheets avoids the curvature set that is created in the roll formation process but this approach loses some of the benefits which rolls provide. Wire mesh products in sheet form require additional packaging to protect the product and to create a package that can be handled by a forklift. Another disadvantage of sheets is that they can be more difficult for the user to handle in the field. A further disadvantage for certain applications such as wire stucco reinforcement is that sheets require additional end overlaps in the construction of a wall. This reduces both the efficiency of application and the quality of installation in comparison to rolls which contain longer continuous lengths.
U.S. Pat. Nos. 3,632,054, 3,688,810, 3,814,144, 4,077,731, 4,557,633, and 5,009,545 all acknowledge the problems associated with wire meshes in rolls and disclose various apparatus and methods for straightening, backbending, decontouring the web and flattening the roll, so that when it is unrolled the tendency of the wire mesh to reassume a rolled position is substantially eliminated. These approaches compensate for the problem of curvature set but they do not avoid the introduction of curvature set in the first place.
The object of the present invention is to reduce the curvature set of longitudinal wires in metallic wire meshes that are wound into rolls for packaging or transport and are intended to be unrolled prior to use.
The present invention has application to wire mesh comprising a plurality of longitudinal strands and a plurality of transverse strands forming a plurality of rectangles, where the longitudinal strands are continuous and the transverse strands are either continuous or segmented, and the mesh or fencing is held together by welding or mechanical fastening at each intersection.